Strict control of blood glucose levels of diabetes patients is very important to prevent onset of a complication such as retinopathy, nephropathy, or neuropathy. Hemoglobin A1c, glycoalbumin, fructosamine, 1,5-anhydro-D-glucitol, or the like has come into practical use, as an index of determination of control status of blood glucose.
Among these indices, glycoalbumin, which reflects the control status of blood glucose for the past 1 to 2 weeks, is thought to be useful for the short-term control, in order to deal with various problems in diabetes control such as the timing of start of drug administration, pregnancy, trauma, and acute complications. 1,5-Anhydro-D-glucitol, which is a polyol present in the human body, is known to be lost when sugar urine is excreted, and concomitantly, blood 1,5-anhydro-D-glucitol level drops rapidly. Therefore, diabetes patients have a considerably low level of 1,5-anhydro-D-glucitol. As is also known, when blood glucose is poorly controlled, blood 1,5-anhydro-D-glucitol level rapidly lowers, and gradually returns to a normal level at a constant rate if good status of blood glucose is continued. Since 1,5-anhydro-D-glucitol also reflects blood glucose variation within a relatively short period and exhibits considerably large variation in a slight hyperglycemia zone, 1,5-anhydro-D-glucitol serves as a useful index for more strictly controlling blood glucose level or for assessing the effect of therapy for diabetes.
When a target component in a specimen is detected, control material whose quality is stable is preferably employed as reference material. However, when a lyophilized control material is reconstituted upon use, deterioration of the component in the control material is problematically caused. This problem is solved by adding a stabilizing agent to control material. For example, sucrose (saccharose) is added as a stabilizing agent for hemoglobin A1c (Patent Document 1), and a disaccharide (e.g., sucrose) is added as a stabilizing agent for glycoalbumin (Patent Document 2).